This invention relates to patterning of metal films, and more particularly to patterning of metal films using surface chemistry mediated transfer processes.
Established fine line lithographic methods (e.g., electron-beam lithography, deep ultraviolet photolithography, etc.) are widely used for patterning metal layers. These processes are mainly subtractive processes. The importance of nanofabrication in a wide range of technologies has created substantial interest in additive techniques, such as those based on forms of contact printing, molding, embossing, and writing. Additive patterning methods are inherently simpler than substractive techniques and the consequent potential cost benefit makes them especially attractive in the manufacture of microelectronic devices.
Recent research demonstrates that additive techniques can produce pattern resolution in the micron and nanometer regime. That makes them especially promising for forming fine metalization patterns, and small electrical circuit features, in microeletronics. Efforts to apply these techniques to the manufacture of thin film transistor (TFT) devices is a special priority.
The invention is an additive printing method that has fine resolution. It involves forming a pattern layer on a transfer substrate, patterning the pattern layer while on the transfer substrate, then contacting the transfer substrate with the receiving substrate. The term receiving substrate is intended to mean the substrate or body where the final pattern is intended, and is typically a polymer. In one embodiment, the transfer substrate is rigid, and the receiving substrate is flexible. The receiving substrate is treated to form a metallurgical bonding layer chemically bonded to its surface. The metallurgical bonding layer comprises small particles of metal. The pattern layer is preferably of the same metal, or a similar metal or alloy, and is transferred from the transfer substrate to the receiving substrate by metallurgical bonding.
The method of the invention is particularly useful for printing metal conductor patterns (metalization) and device features on flexible polymer substrates in TFT technology.